Loss of power

Does it iddle at 1800-2300 RPS? If so have the TPS changed.

There is a vacuum advance attached to the distributor. Inside the vacuum advance is a rubber diaphragm that can crack from age an no longer work. Sometimes the vacuum hose that attaches to it may not be getting proper vacuum. This device adjusts your timing when you accelerate. Improper function could cause the problems you describe. Also, a vacuum leak in any of your vacuum system could cause the problem your describing. Too much air intake on take off from a faulty vacuum system could throw off your air fuel mixture on acceleration causing hesitation until the air fuel mixture can catch up which is when the power comes back. Hope this helps.

Sounds like possible ignition misfire. Go to an autozone or parts store that will scan the engine management system for free and repost what the codes are then we can help further

ENGINE HESITATES WHILE ACCELERATION
LOSS OF ACCELERATION

It can be fuel pressure issue or it's the problem with accelerator pedal or its clogged filters causing there.
There are many other possibilities. I suggest you to go through the list of help links mentioned below, these will help you to confirm where the actual fault lies: -------
Jerks and Hesitates During Acceleration?
http://technoanswers.blogspot.in/2012/07/2004-dodge-town-country-jerks-and.html
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Loss of acceleration?
http://technoanswers.blogspot.in/2012/02/loss-of-acceleration.html
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Headlights flickering and car hesitates to start?
http://howtobyme.blogspot.in/2012/02/headlights-flickering-and-car-hesitates.html
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How exactly the Vehicles Accelerator Cable works?
http://repairhelpcenter.blogspot.com/2011/11/how-exactly-vehicles-accelerator-cable.html
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How exactly Vehicles Accelerator Pump Diaphragm Works?
http://repairhelpcenter.blogspot.com/2011/11/how-exactly-vehicles-accelerator-pump.html
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2000 Toyota Avalon: Engine Lean Codes and Knock Sound on Acceleration?
http://whatisbyme.blogspot.in/2012/05/2000-toyota-avalon-engine-lean-codes.html
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2004 Toyota Avensis: Acceleration And Deceleration makes noise on Front End?
http://whatisbyme.blogspot.in/2012/05/2004-toyota-avensis-acceleration-and.html
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Wheel hop under hard acceleration?
http://technoanswers.blogspot.in/2012/04/wheel-hop-under-hard-acceleration.html
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2009 Chevy impala accelerator pedal sensor?
http://technoanswers.blogspot.in/2012/02/2009-chevy-impala-accelerator-pedal.html
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Nissan Pathfinder stalls and bucks on Acceleration?
http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-stalls-and-bucks-on.html
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Acceleration lag problem?
http://repairhelpcenter.blogspot.com/2012/01/acceleration-lag-problem.html
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These details will help.
Thanks.

1) Val adjustment is set too tight
2) engine ha worn camshaft lobe.bent push rods or worn valve lifters
3) loss of power in one or more cylinders due to defects in ignition system
4) intake manifold system is leaking
5) air cleaner dirty
6) leaky valves.
7) fuel mixture is too lean or too rich
8) fuel pump is defective.
God bless you

Normally that would be classic vapor lock. But I don't know how that could happen since fuel injection recirculates so much? I try to think of how gas tank vent valve could do this and also draw a blank. Leaving the fan. It is electric and possibly not working? It is mechanical and have a bad clutch?

fuel filter couldn't be removed huh !!! hmmm i think there would be no better place to start with than the fuel filter then onto the air filter etc ..but replace the fuel filter for sure

Start with IAC motor, TPS sensor, possible clogged catalytic converter.

I found this; if it helps.
The injectors need to be cleaned, if an engine is experiencing any of the classic symptoms of dirty injectors, such as lean misfire, rough idle, hesitation and stumbling on light acceleration, a loss of power, and higher hydrocarbon (HC) and carbon monoxide (CO) emissions.
Lean misfire may also trigger a misfire code and turn on the Check Engine light on 1996 and newer vehicles with OBD II systems. The code often will be a P0300 random misfire code, or you may find one or more misfire codes for individual cylinders, depending on which injectors are most affected.

the web page was:
http://www.aa1car.com/library/2003/ic30336.htm

Hope this helps

i would suggest checking your fuel pressure first